I have an L couch in the front and my inverter is under the left front bunk, where the battery cables come into the trailer. They need the 12v
fused line right from the battery.
The PO blew out the internal fuses in mine and as long as they were out, no red light on the panel. Once I replaced the fuses the light came on and the outlets were hot again. I'm not sure why you have the red light but no voltage at the outlets. Are you plugged into the inverter outlets? Not all of the outlets are linked to the inverter, just a few and are labeled.
Look for the inverter close by the wall where the battery cables come in. There are 2 heavy cables for the 12v
input, then a flat house style wire coming out, about 14 gauge. On mine, the wires feed into a plug that then continues on to the outlets (I assume, may go elsewhere first). I'd check the voltage at the 110 vac connection just outside the inverter. Also coming off the inverter is the small wire, looks like phone wire, that goes to the control panel with the red light.
You might have to open the inverter and replace 2 automotive style mini fuses; mine were 35 amp. I had to order mine online because I found 30 and 40 at the store but not 35. I'm using 30 right now and they work OK for my needs.